Sander Having a Brushless Motor

ABSTRACT

A sander may include a wand having a proximal end and a distal end, a sanding head mounted to the proximal end of the wand, and a brushless motor mounted on the distal end of the wand that is configured to provide rotational motion to the sanding head.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/763,961, filed on Feb. 1, 2006, and titled“Sander Having A Brushless Motor”, which is incorporated by reference inits entirety.

TECHNICAL FIELD

This description relates to a motorized sander having a brushless motor.

BACKGROUND

A motorized sander may be used to remove material from various types ofsurfaces. For instance, the motorized sander may be used to removematerial from drywall surfaces, concrete surfaces, wood surfaces, andother surfaces. Additionally, the motorized sander also may be used forscuffing or roughing up a painted surface prior to applying another coatof paint. In addition, it may be used as a floor buffer, a device forremoving barnacles on fiberglass boats, removing textures on a ceiling,wallpaper, and wallpaper paste as well as other assorted planar surfacesanding operations. During the removal process, the environment maybecome contaminated. For example, when removing joint compound from adrywall surface, the environment may become contaminated with dust andother contaminants. Motorized sanders that include brush-type motors mayrun continuously for long periods of time in environments that containhigh levels of contaminants. In a brush-type motor, the motor housingtypically includes a fan within the motor housing to cool the stator andthe rotor by providing air flow within the motor housing. The dust andother contaminants are constantly being circulated through the airstream of the brush-type motor which may result in frequent brushchanges and low overall tool life, both of which may cause frequent downtime and lost productivity for the user.

DESCRIPTION OF DRAWINGS

FIG. 1 is an isometric view of an exemplary motorized sander.

FIG. 2 is an exemplary cut-away view of a housing with an installedbrushless motor.

FIG. 3 is an assembled view of an exemplary brushless motor.

FIG. 4 is an exploded view of an exemplary brushless motor.

FIG. 5 is an exploded view of an exemplary brushless motor.

FIG. 6 is an exemplary schematic wiring diagram.

FIG. 7 is an isometric view of an exemplary electronic control module.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

In one exemplary implementation, a motorized sander includes a brushlessmotor. The brushless motor may include a brushless direct current (DC)motor or a brushless alternating current (AC) motor. In a brushlessmotor, the rotation of the rotor is produced and controlled without theuse of one or more high wear components such as, for example, thebrushes and a commutator. Additionally, one or more of the brushlessmotor components may be enclosed and/or sealed within a motor housing ora motor pack. The motor housing or motor pack may not include a fanwithin the motor housing or the motor pack and thus, there would be noair flow within the motor housing or motor pack. This would eliminatethe dust and other contaminants from being circulated within the motorhousing or motor pack. To provide cooling for the motor housing or themotor pack, a fan may be connected external to the motor housing ormotor pack and provide air flow over the motor housing or motor pack butnot within the motor housing or motor pack.

Provided below is an exemplary description one or more implementationsof a brushless motor in a motorized sander. The exemplary description isnot meant to be limited to a specific type of sander. Instead, thebrushless motor also may be implemented in other types of motorizedsanders.

Referring to FIG. 1, a motorized sander 100 may include a hose clamp nut102 attached to a vacuum adapter housing set 104 which in turn may beattached to a distal end 106 of a dual chamber tubular wand 108. Thetubular wand 108 also may include a proximal end 110.

In one exemplary implementation, the motorized sander 100 may include ahousing 112 that houses a brushless motor 113. The housing 112 mayinclude one or more air vents 117 to enable air flow through the housingand around the motor pack of the brushless motor 113. The brushlessmotor 113 may be coupled in-line with the tubular wand 108. Thebrushless motor 113 may be mounted at the distal end 106 so that sander100 has a balancing point near the middle of the length of tubular wand108 when a sanding head 118 is attached to the proximal end 110. Thebrushless motor 113 may be a variable speed brushless motor. Thebrushless motor 113 includes an on/off toggle switch 114. In oneimplementation, the motor speed may be varied by a variable speed thumbwheel switch 116 located on the opposite side of the tubular wand 108from the on/off switch 114.

The dual chamber tubular wand 108 may include a first lower chamber anda second upper chamber which extend along the length of the tubular wand108. A flexible drive shaft within the tubular wand 108 may be coupledto the brushless motor 113 and extend along the length of tubular wand108 towards the proximal end 110 within the first chamber. The flexibledrive shaft may receive rotational energy from the brushless motor 113and impart the rotational energy to the sanding head 118. A vacuum linemay extend through the second chamber from the proximal end 110 to thedistal end 106 to the vacuum hose clamp 102. This vacuum line within thesecond chamber may be completely separate and sealed from the firstchamber of the tubular wand as well as being sealed from the brushlessmotor 113.

The sanding head 118 may be mounted by a pivotal joint to the proximalend 110 of the tubular wand 108. The sanding head 118 may include asanding drive plate that is coupled to the flexible drive shaft. Theflexible drive shaft may not be securely fastened to the sanding driveplate, but rather may be loosely fit into a slotted drive hole within athreaded spindle which allows the flexible drive shaft to move back andforth between the sanding head 118 and the brushless motor 113 as thesanding head 118 is pivoted/bent into various positions. The pivotaljoint may include a first flexible joint and a second flexible joint.The first joint may be configured to pivot about a first axis which isdifferent from a second axis about which the second joint pivots. In oneexemplary implementation, the first axis is perpendicular to the secondaxis.

Referring to FIG. 2, a cut-away view of an exemplary housing 112 isillustrated. The housing 112 is in-line with the tubular wand 108. Thehousing 112 houses the brushless motor 113. The housing 112 includes oneor more air vents 117 to provide air flow to cool the brushless motor113. In one exemplary implementation, the power on/off switch 114 andthe variable speed switch 116 may be connected to the housing 112 withinternal connections to components within the housing 112.

The output of the brushless motor 113 may be connected to one or moregears 261, which may be enclosed by a gear case cover 262. The gears maybe connected to an output shaft 265 that provides rotational energythrough the flexible drive shaft to the sanding head assembly. Thehousing may include a baffle 267 to direct air flow over the brushlessmotor 113. The brushless motor 113 also may be connected to a capacitor270.

Referring to FIGS. 3-5, exemplary views of the brushless motor 113 areillustrated. The brushless motor 113 includes a housing 305 thatencloses the stator and rotor subassemblies. The stator sub assemblyincludes the stack 310 and windings 315. Laminations may be bondedtogether and then coated with insulating material. In one exemplaryimplementation, the stack 310 may be a 20 mm stack length. The windings315 are wound over the stack 310. The stator sub assembly may be pressfit inside the housing 305.

The rotor sub assembly includes a bottom bearing 320, shaft 325, one ormore rotor magnets 330, rotor 335, sense magnet tray 340, one or moresense magnets 345 and a top bearing 350. The bottom bearing 320 may bepress fit on the shaft 325. The rotor 335 may be press fit on the shaft325 from the other side and the rotor magnets 330 may be glued to thesense magnet tray 340. The top bearing 350 may be press fitted on theshaft 325. The bottom bearing 320 may be push fitted inside a bearingpocket of the housing 305.

The stack 310 and windings 315 enclose the rotor sub assembly providinga rotating magnetic field that the rotor sub assembly magnetic field isdrawn towards. The bottom bearing 320 and the top bearing 350 provide amechanical interface to permit rotation of the rotor sub assembly.

The sense magnets 345 may provide a marker of the relative position ofthe windings 315. A sensor card 360, which may be connected to a sensorcard spacer 355, may include multiple Hall sensors that are spaced apartto detect the sensor magnets 345 as the shaft 325 rotates.

A motor spacer 365 may separate rotor and stator sub assemblies from anelectronic control module 370, an electronics end cap 375, a bushing370, and a fan 390. The electronic control module 370 may include one ormore components to that may be configured to control the rotor andstator sub assemblies. The electronic control module 370 may include awire holder 380. The electronic control module 370 may be potted. One ormore fasteners 395 may be used to fasten one or more components of thebrushless motor 113 together. The fasteners 395 may be used to stop theaxial movement of the fan 390.

FIGS. 5 and 6 illustrate the electrical connections within the brushlessmotor 113. An electrical connection is made from the windings 315 to theelectronic control module 370 and from the Hall sensors on the sensorboard 360 to the electronic control module 370. The switch 114, speedcontrol 116, capacitor 270, and power supply 605 also may beelectrically connected to the electronic control module 370.

FIG. 7 illustrates the electronic control module 370 that iselectrically connected to capacitor 270 and includes multiple electroniccontrol components including, for example, MosFETs 770.

Other implementations are within the scope of the following claims.

1. A sander comprising: a wand having a proximal end and a distal end; asanding head mounted to the proximal end of the wand; and a brushlessmotor mounted on the distal end of the wand that is configured toprovide rotational motion to the sanding head.
 2. The sander of claim 1wherein the brushless motor is a direct current (DC) brushless motor. 3.The sander of claim 1 wherein the brushless motor is an alternatingcurrent (AC) brushless motor.
 4. The sander of claim 1 wherein thesanding head is mounted by a pivotal joint to the proximal end of thewand.
 5. The sander of claim 1 further comprising a drive shaftextending a length of the wand that is coupled to the sanding head andthe brushless motor.
 6. The sander of claim 1 further comprising a motorhousing enclosing one or more components of the brushless motor.
 7. Thesander of claim 6 further comprising a fan mounted external to the motorhousing.
 8. The sander of claim 6 further comprising a sander housinghaving at least one vent and substantially enclosing the motor housing.